It is customary around the production and refinement of petroleum products to burn or "flare" waste gases. These waste gases can be the natural byproducts of oil production. They can also be produced through the refinement of raw oil into more suitable forms. Waste gases include many low BTU hydrocarbons, hydrogen sulfide (H.sub.2 B), carbon monoxide and even carbon dioxide. The combustion of these waste gases converts them into a more inert form.
State and federal air quality regulations mandate the ignition of waste gases to prevent their release into the atmosphere. Moreover, this ignition must be maintained during the venting of these gases. Particular care must be exercised to prevent the ignition of the waste gases from blowing out, leaving only uncombusted waste gases exhausting into the atmosphere. An ignitor device provides a source of flame to ignite or reignite waste gases.
Ignitor devices encounter several problems. Namely, high winds can blow out their flame as well as the flame from combusting waste gases. High winds can also cause "flame-lick" in which the flame is blown down the sides of the pipe. The flame licking back down the pipe may actually damage or destroy the ignitor device and flare pipe. The fire problem is particularly pointed out in U.S. Pat. No. 2,661,798 to Clevenger, et al. and in U.S. Pat. No. 2,537,091 to Rodman, et al., both of which describe steps to protect the ignitor from the damage of flame-lick. These steps have often resulted in a loss of reliability.
The ignition of the waste gas may also be extinguished due to the low BTU value of those gases. Their own burning does not provide enough heat to maintain the combustion. Also, the combustion of the waste gas may be affected by the velocity with which waste gas exits the flare pipe. High velocity exhaust may cause the flame to "lift-off" from the top of the flare pipe. The flame will then self-extinguish for lack of additional combustible gas.
Another problem is present with ignitor devices used during the drilling and production of oil and gas wells. In such cases, the gases to be burned come directly from the well and through a stack or flare pipe. Unfortunately, water, mud and heavy petroleum products having low volatility and high viscosity will be emitted through the stack intermittently with the production of gases. These liquids which are either incombustible or not readily combustible will put out the flame if one is already burning. In addition to this, the liquids may flow into the ignitor, filling the ignitor. This clogging will prevent the fuel/air mixture used to produce its flame from flowing into the combustion chamber.
Ignitor devices in the prior art also are deficient in their ability to notify operators that combustion has ceased. State and federal laws often mandate a reliable notification method to signal ignition failure. In response to the problem of ignition failure, various devices have been used to detect when the ignition of waste gases has ceased. A thermocouple can sense the drop in heat, but must cool down before it will reignite the ignitor. Infrared or ultraviolet sensors can also detect the presence of a flame. However, these devices require a great deal of maintenance to insure their reliability.
A need exists for a simple and reliable ignitor device capable of igniting and automatically re-igniting waste gases. Such an ignitor should be able to provide a flame incapable of being blown out by high winds. Such an ignitor should also be designed so that fluids cannot clog it. Additionally, an ignitor is needed which provides a stable environment for the burning of waste gases by inhibiting flame lift-off.